The present invention relates to a particle removing arrangement adapted to remove particles in front of a current collector on an electric vehicle. The particle removing arrangement is suitable for electric vehicles and hybrid vehicles having a rechargeable battery.
The share of partly or only electrically driven vehicles is expected to increase radically in the next 10 to 20 years. Such vehicles are normally referred to as electric vehicles and hybrid vehicles. This also means a corresponding increase in the need to charge such vehicles. In principle, the charging is done by connecting the vehicle to the electrical network, either directly to one of the ordinary outlets used for other equipments, or through a special charger, external to the vehicle. Charging current is transferred from the network to a battery on board the vehicle.
The battery of the electric vehicle may be charged with a relatively low current over a relatively long time period, e. g. over night. Such vehicles are referred to as plug-in vehicles and are common for hybrid vehicles which are provided with a battery having a relatively low capacity, such that the distance that the vehicle can travel on electric power is limited. When the battery is empty, or when additional power is required, the combustion engine is started. High current charging of plug-in vehicles is also possible. Since the vehicle is charged one or two times a day, a specific connector is used to connect the vehicle to the current source.
The use of a connector for charging the vehicle is possible for vehicles that are not used very often, such as passenger cars. In such a case, the vehicle may be charged at home over night and at work during daytime.
For vehicles that require charging several times a day, such as commercial vehicles, a connection by using a plug is not an efficient alternative. Instead, various types of current collectors are proposed, which are connected to an external current supply means when the vehicle is stopped, such as a bus at an end stop. This will work for vehicles that have a lot of planned stops at specified positions, such as city buses or delivery trucks.
This is however not a solution for vehicles driving long distances, such as long haul trucks or long distance busses. It is proposed to arrange “electric highways” where a vehicle can connect to a current supply when driving. One possibility is to use overhead current collectors that connect to an overhead wire system. Another possibility is to apply contact rails in the surface of the road, where current collectors of the vehicle slide against the upper surfaces of the contact rails. Two rails are positioned side by side in order to provide two electric poles. It would also be possible to combine the two, by using one overhead electric wire and one electric rail. In such a system, the overhead wire would supply the voltage and the electric rail would be the ground or neutral pole.
One problem with electric rails embedded in the road surface is to keep the upper surface clean from water, dirt, leaves, gravel and other particles in order to provide a good contact between the electric rail and the current collector. Larger objects, such as stones, dead animals etc. can be removed by the use of a plough-like member in front of the current collector, preferably at the front of the vehicle. Such a plough-like member must however ride at a small distance above the road surface and is thus not suited to remove smaller objects like water or small stones etc. having a size of less than 1-2 centimeters. Small objects will decrease or break the contact between the electric rail and the current collector and they may also damage the current collector, since the vehicle may travel with a high speed.
There are different solutions for the removal of smaller objects from an electric rail. One solution is to direct a pressurized air flow to the upper surface, where the pressurized air is provided by an air compressor driven e. g. by the engine of the vehicle. Such a solution consumes a fair amount of energy. Another possibility is to use a plough or brush in sliding contact with the electric rail. Such solutions will be subjected to wear and need constant maintenance. One solution would be to use contact brushes as current collectors, but such a solution is not adapted for higher currents.
WO 2003/104016 shows a current track embedded in the road surface. The current tracks are provided with grooves in which current pick-ups of a motor vehicle are guided at the same time as current is collected. The current pick-up may be provided with a plough and a nozzle in order to remove dirt. The plough is positioned directly in front of the current pickups. A small nozzle is also positioned directly in front of the current pick-ups and is arranged to direct the airflow downwards and forwards into the current grooves. In this way, the dirt will accumulate in front of the current pick-ups in the current groove. This solution may work for small amounts of dirt because some part of the flow jet may diffuse sideways.
There is thus a need for an improved particle removing arrangement.
It is desirable to provide an improved particle removing arrangement for a current collector of an electric vehicle.
In a particle removing arrangement according to an aspect of the invention adapted to remove particles from the upper contact surface of an electric rail comprised in an electric highway by the use of an airflow, where the particle removing arrangement is arranged in front of a current collector of a vehicle, where the particle removing arrangement comprises an inlet opening for inlet of air and an outlet opening for outlet of air, the inlet opening is directed in a forward direction and the outlet opening is directed in a sideway to rearward direction in relation to the driving direction of the vehicle, and in that the particle removing arrangement creates a particle removing airflow from a forward movement of the vehicle.
By this first embodiment of the particle removing arrangement according to the invention, the particle removing arrangement is adapted to create a particle removing airflow where the outlet opening is directed in a sideway to rearward direction in relation to the driving direction of the vehicle. In this way, the airflow is directed such that the airflow directs the dirt away from the electric rail. In this way, the dirt will not accumulate in front of the current collector, which will improve the reliability of the electrical connection between the electric rail and the current collector. This is advantageous since each electric interruption in the electrical connection will cause a disruption in the charging of the vehicle battery and may also cause an electric arc which may damage the contact surfaces.
The particle removing arrangement may be positioned close to the current collector and may be arranged on the current collector sub-frame, such that the particle removing arrangement will follow the alignment of the current collector in a sideway direction, and also when the current collector is raised to an idle position. The particle removing arrangement may also be positioned at a distance in front of the current collector. In one example, the particle removing arrangement is arranged at the front of the vehicle, close the bumper and the current collector is arranged at the rear of the vehicle, at the rear axle of the vehicle. In another example, the particle removing arrangement and the current collector are both arranged next to the front axle of the vehicle.
In a development of the particle removing arrangement, the particle removing arrangement is provided with a first low, active position where it is positioned adjacent the upper contact surface of the electric rail. In this position, the particle removing arrangement will remove dirt form the upper surface of the electric rail. The particle removing arrangement is further provided with a second idle position in which the particle removing arrangement is raised upwards from the first, lower position. In this position, the particle removing arrangement will not remove any dirt from the electric rail. This position is preferably used when the vehicle is driving on a road that is not provided with an electric rail. This position may also be used if several vehicles travel after each other, and the first vehicle uses a particle removing arrangement. In this case, the electric rail has been cleaned by the first vehicle.
In one embodiment, the particle removing airflow is a blowing airflow, which is directed towards the upper surface of the electric rail. The inlet opening is directed forwards and the outlet opening is directed sideways to rearwards, i. e. in a direction between 90 and 180 degrees in relation to the driving direction of the vehicle. The inlet opening is larger than the outlet opening, such that a funnel-shape is obtained. The funnel-shape will collect the incoming airflow and will accelerate the airflow to an airflow having a higher speed.
In another embodiment, the particle removing airflow is a suction airflow, where the particle removing arrangement comprises a particle inlet positioned above the upper contact surface of the electric rail. In this way, dirt will be sucked from the upper surface of the electric rail by the particle inlet, functioning with an ejector effect. The flow channel of the particle removing arrangement preferably comprises an area reduction of the flow channel at the particle inlet in order to increase the ejector effect. In one example, the area of the inlet opening is the same as the area of the outlet opening. In this way, the energy loss through the particle removing arrangement will be minimized. The outlet opening is preferably directed away from the upper contact surface of the electric rail such that the outlet air flow is not directed towards the electric rail. The outlet opening may be positioned sideways of the upper contact surface of the electric rail, offset in a sideway direction with regards to the inlet opening, with the outlet opening directed rearwards. In this way, the outlet air flow and the particles are blown out at the side of the upper contact surface. The outlet opening may also be directed sideways with an angle to the travelling direction of the vehicle such that the outlet air flow is directed away from the upper contact surface of the electric rail.